An elevator and a possible counterweight are suspended in an elevator hoistway on suspension ropes. The force for driving the elevator car is produced with a rotating hoisting machine, and the force produced is transmitted to the elevator car/counterweight with ropes that travel in the rope grooves of the traction sheave of the hoisting machine. The same ropes can be used for both the suspension and the driving of the elevator car; on the other hand, the elevator system can also comprise wholly or partly separate ropes for the suspension and for the driving of the elevator car. In addition, the elevator system can also comprise, inter alia, one or more compensating ropes, the purpose of which is to reduce the force difference caused from the asymmetrical weight distribution of the elevator roping on the different sides of the traction sheave.
One or more rotating diverting pulleys, via which the ropes pass, can be fixed to the structures of the elevator hoistway, to the machine room (if an elevator system with machine room is involved) and into connection with the elevator car and the counterweight. By the aid of the diverting pulleys both the passage of the ropes can be guided and the suspension ratio can also be changed, which affects the magnitude of the rope force caused from the load to be moved.
In addition to a hoisting machine/diverting pulleys, the elevator system also comprises other parts, which when operating rotate at their certain natural frequency. Such parts are e.g. the rotor of the drive machinery of the door of the elevator car and also the track rollers, which support and guide the movement of the door panels in connection with opening/closing of the door.
The components belonging to an elevator assembly wear and might also fail over the course of time. For example, wearing of the bearings of the hoisting machine and of the diverting pulleys might cause noise problems and gradually also a deterioration of the ride comfort of the elevator. The noise caused from operation of the door operator can increase to be disturbing when the operating condition of the bearings of the rotor of the door operator and of the bearings of the track rollers deteriorates. Also damaging of the coating of the traction sheave, a diverting pulley and a track roller might cause a noise problem/weaken ride comfort.